With the technological advances that have been made in camera technology, including the development of miniature and solid state digital cameras, it has been increasingly commonplace to incorporate video cameras into ordinary diagnostic equipment. One specific application of the modern cameras is in the field of robotics, and remote inspection systems. For instance, cameras may be incorporated into robotically controlled electronics manufacturing systems for inspection of solder or weld joints, for examining the proper placement of components in electronic assembly, and other uses where visual feedback would be advantageous.
Another practical application of modern camera technology includes the inspection of hazardous environments. For instance, a video inspection system can provide a more detailed inspection than the naked eye, can be exposed to environments incompatible with human life, and can often identify defects long before they become apparent to less sophisticated inspection systems. These defects, if left unnoticed, can result in significant safety hazards, and in some environments, can lead to catastrophe. One such environment is in the inspection of tanks used for the transport and storage of hazardous materials, such as fuel tanks, oil tanks, or other dangerous chemicals.
Hazardous environments that contain volatile gasses, vapors, or liquids are typically classified by zones. Specifically, a Zone 2 environment has no risk of fire or explosion, Zone 1 has a higher risk of fire or explosion, and Zone 0 has a high risk of fire or explosion. Equipment is typically certified to operate in specific zones. For instance, one device may be certified only for use in Zone 2 environments, while another device may be certified for use in Zone 1. Typically, devices certified for Zone 1 can also be used in Zone 2 since Zone 2 has less stringent requirements for safety than Zone 1.
In order to satisfy the requirements for Zone 1 and Zone 0, certain electrical and mechanical design requirements must be met. These design requirements are primarily focused on safety concerns, and include the limitations to avoid excessive heat, fire, spark, static, or other sources of ignition. Devices that are designed for use within the Zone 0 environment are considered “intrinsically safe.”
Intrinsic safety is a protection model employed in potentially explosive atmospheres and relies on the electrical apparatus being designed so that it is unable to release sufficient energy by either thermal or electrical means that can cause an ignition of a flammable gas. A published discussion of this protection technique can be found at www.iec.ch. Part of IEC 60079 specifies the construction and testing of intrinsically safe apparatus intended for use in an explosive gas atmosphere and for associated apparatus, which is intended for connection to intrinsically safe circuits which enter such atmospheres. These are locations where ignitable concentrations of flammable gases, vapors, liquids, dust, or easily ignitable fibers are present continuously, or are present for long periods of time.
Historically, video systems have been excluded from being used in Zone 0 applications due to the potential for an explosion. Typical video systems include sufficient voltage potentials and power uses that can create excessive sparking, localized heat sources, and in some cases, a circuit failure could result in a fire developing within the video system itself causing a primary explosion. This is particularly dangerous when considering the highly volatile Zone 0 environments where a primary explosion would necessarily result in a more catastrophic secondary explosion.
In order to inspect Zone 0 or Zone 1 environments, it is estimated that millions of dollars spent each year are expended in the opening, gas-freeing and inspection of vapor and gas storage and transportation tanks. This estimate does not take into account the substantial amount of time required to prepare permits, secure the area, evacuate the tank, and send in a person wearing HAZMAT equipment inside the tank with conventional recording and inspection equipment. Many of these are unplanned and could have been unnecessary.
In light of the above, it would be advantageous to provide a video inspection system that offers a multifold increase in process efficiency from reduction in time and cost in tank opening, gas-freeing, and inspection. In addition, it would be advantageous to provide a video inspection system that offers quantitative and standardized inspection analysis and results which are not subject to human judgment, error or variability. Cost savings associated with such a video inspection system would include a substantial reduction in labor costs that are typically associated with the insertion of trained inspectors into these confined spaces and the unnecessary ventilation and re-preservation of tanks.